Azure AD Sync behind proxy

To be able to have Azure AD Sync (AADSync) behind a proxy it must allow unauthenticated proxying (i.e. no ID/PWD). If you can fulfill this then you need to do the following:

1. Configure the proxy server
2. Configure AADSync to use the proxy server

Configure the proxy server

Do configuring to allow traffic to Office 365 IP's and URL's.

Configure AADSync

If you have a static ID/PWD for the service account then use the following command:

runas /user:domain\serviceuser "control.exe inetcpl.cpl"

In some cases you also need to edit the machine.config for .Net framework 4.5

1. Open C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config\machine.config
2. Add proxy settings (case sensitive XML)

Example on proxy settings
<system.net>
<defaultProxy>
<proxy usesystemdefault="true" proxyaddress="http://proxy-ip:80" bypassonlocal="true" />
</defaultProxy>
</system.net>

Reference: 

• Element (Network Settings) 
• Element (Network Settings)
• Office 365 URLs and IP address ranges
• AADSync - AD Service Account Delegated Permissions

Sometimes you also need to set winhttp using NetSh
set proxy proxy-server="http=myproxy;https=sproxy:88" bypass-list="*.contoso.com"
NetSh commands